def load_index(index_path, train_path, reconstruct=Setting.RERUN):
print "load or construct index..."
if not reconstruct and os.path.exists(index_path):
index = load_data(index_path)
else:
index = Index()
index.train_path = train_path
index.construct_index()
dump_data(index, index_path)
print "done!"
return index
